Motorcycle takes out two cyclists...

[Geriatrix]

I'm a helmet sceptic but prepared to believe that, in this very atypical accident, we may have an instance in which a helmet helped - although there's still the risk to the neck of a larger "head" causing more violent rotation. We'll never really know.

+1

I don't know if a helmet would have helped in this instance but I personally would rather have been wearing one than not.

It's a personal choice and it doesn't change my stance on helmet compulsion which is no! It's a matter of evaluating the risk. I mostly don't wear a helmet (never worn one on a recumbent) but there are some occasions where I wear one if I think its appropriate. That's mostly when I know I am going to be pushing the limits of my abilities and there is an increased chance of a fall or collision.

[[XAP]Bob]

I suspect that the helmet has at least prevented some lacerations and may even have reduced the skull force dramatically, but it has also undoubtedly increased the rotational acceleration at various points in this collision - we're in no position to declare one way or the other, but if I was riding such an out of date design of bike and was hit in a completely freak accident like this then I'd probably be happy wearing the thing.

Certainly the main concern of the paramedic crouched behind him at around 2:15 while he makes his statement is to stabilise his neck and as someone has said there is little visible evidence of impact crushing of the helmet. Unless they want to repeat the incident though without helmets we will never know but hitting the back of the head is one of the main causes of pedestrian deaths in trips and slips so perhaps an equally good reason for them to wear one too.

This, by the way, is the exact moment of first impact with the road:

Screen Shot 2013-05-02 at 07.20.24.png

At this point the force on the head is basically used to rotate the neck, and hence to reduce the rotation of the body to some small extent, but a tiny fraction of a second later the shoulders take on all that force, and I don't think the head contacts the ground again. The body is clearly still rotating as he ends up with his feet bouncing off the road behind his head and a curve of the spine that would make a contortionist envious.
The next (and previous) few frames are equally instructive - mostly because it's not a static event.

I do *not* suggest that anyone tries this without a helmet, but then I wouldn't suggest that anyone tried it *with* a helmet either.

[kwackers]

I know my personal tally of crashes is too few to be statistically significant, but as far as I can recall, all those involving contact between head and tarmac (4) were face plants. Does that tell us anything?

Yep, try sticking your hands out to arrest your fall...

[Ellieb]

I know my personal tally of crashes is too few to be statistically significant, but as far as I can recall, all those involving contact between head and tarmac (4) were face plants. Does that tell us anything?

1: you need to stop cycling into things
2: you need to get your weight back a bit more
3: you are not as handsome as you once were

[TonyR]

I know my personal tally of crashes is too few to be statistically significant, but as far as I can recall, all those involving contact between head and tarmac (4) were face plants. Does that tell us anything?

Yes, dress like The Stig. You know it makes sense.

[TonyR]

At this point the force on the head is basically used to rotate the neck, and hence to reduce the rotation of the body to some small extent

Increase shurley?

[661-Pete]

Why thanks guys for all your feedback - some great ideas there! I'll address them one by one:

Yep, try sticking your hands out to arrest your fall...

Ja, but vif all ze fingers gebroken, how zen am I ze vunderbar Hammerklavier Sonata von Beethoven going to be playing?*

1: you need to stop cycling into things
2: you need to get your weight back a bit more
3: you are not as handsome as you once were

1. Aha! I knew there was something solid about that lamp-post...
2. I have plenty of weight already, both at back and front...
3. Ah but I am handsome (in my dreams)!

Yes, dress like The Stig. You know it makes sense.

I'd sooner dress like Neil Armstrong. At least he went places...

*As badly as I do now, I expect...

[[XAP]Bob]

At this point the force on the head is basically used to rotate the neck, and hence to reduce the rotation of the body to some small extent

Increase shurley?

Nope - the body is rotating - the action at this point is to slow that rotation (relative to the ground, not the neck)